• It is a series of cyclic changes occurring in the reproductive tract of female with the periodicity of 28 days
• It is also known as menstrual cycle,
• also known as endometrial cycle
• It occur From puberty to menopause
• It is characterized by loss of vaginal blood (breaking of endometrium wall of uterus)
• The cycle is under Influenced of hormones secreted by pituitary gland (FSH and LH), and ovary (progesterone and oesterogen).

Complete in 3 phase

1. Menstrual phase
2. Proliferative phase or follicular or ovulatory phase
3. Luteal or secretory phase

Figure: Menstrual cycle

Menstrual phase

• This phase is characterized by discharge of blood, connective tissues and mucus due to cast off of epithelial lining of endometrium wall
• It Lasts for 3-5 days
• Ovum remain unfertilized,
• At this time level of oestrogen and progesterone is very low in blood resulting in Breaking of endometrium wall of uterus
• About 50-100 ml blood with mucus are discharges as menstrual flow.

Proliferative phase

• This phase is characterized by rapid proliferation and repair of damaged endometrium wall
• It Lasts for 9-10 days (5^th – 14^thdays)
• Anterior pituitary gland release Follicular stimulating Hormone (FSH) which stimulates development and maturation of grafian follicle. So, it is also known as Follicular Phase.
• Mature grafian follicle secrete oestrogen. Its level gradually increases and maximize at 12^thday
• Oestrogen stimulate endometrium repair and proliferation. It also stimulate Ovulation
• Endometrium become 2-3 mm thick and highly vascular

Luteal phase

• This phase is characterized by release of Ovum from mature graffian follicle which is stimulated by the secretion of luteinizing hormone (LH) by pituitary gland.
• It Lasts for 12-14 days (14^th-28^th day)
• LH along with FSH stimulate ovulation.
• Mature graffian follicle release ovum and the rapture follicular cell form corpus luteum
• Corpus luteum secrete progesterone, high level of progesterone inhibit maturation of any other follicles
• Progesterone also stimulate thickening of endometrium wall
• When ovum remain unfertilized, corpus luteum degenerate; level of both hormone (progesterone and oestrogen) decreases, causing breaking of endometrium wall continuing the menstrual phase.

Ovarian cycle (Menstrual cycle)

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